The invention relates to a ball-and-socket joint, in particular for a swivel support for use in an automobile.
Ball-and-socket joints are used, for example, in swivel supports to dampen or prevent force- or torque-induced reaction movements of, for example, drive trains, engines or drive train components in automobiles.
A ball-and-socket joint is described, for example, in U.S. Pat. No. 6,190,080 B1. This ball-and-socket joint has a joint housing in form of a hollow cylinder, wherein a bearing shell made of plastic is inserted in its interior space for slidingly receiving a swivel ball arranged on a ball pin. The bearing shell of the ball-and-socket joint described in the above-referenced patent is supported in the axial direction of the joint housing on two circumferential annular shoulders located on the two end faces of the joint housing.
The first of the two circumferential annular shoulders is initially formed on the plastic bearing shell, whereas the second annular shoulder of the bearing shell that faces the first annular shoulder in this conventional ball-and-socket joint is implemented as a ring-shaped snap connection that is stabilized by an additional cover that is pressed into the second annular shoulder.
In other words, the conventional ball-and-socket joint is assembled by inserting the bearing shell into the housing so that the first annular shoulder is supported on a first end face of the joint housing, whereas the second annular shoulder is realized by snapping together the ring-shaped snap connection and subsequently pressing the safety cover on.
Other known techniques for anchoring the bearing shell in the joint housing produce the second annular shoulder, for example, by forming a flange with an ultrasound technique, or employ safety rings or locking rings for anchoring the bearing shell in the joint housing in the axial direction. It is also known, for example from DE 199 14 452 A1 and U.S. Pat. No. 5,855,448 to form the bearing shell and the joint housing with matching conically contours, and then inserting the bearing shell into the joint housing up to an axial limit stop. The bearing shell is pretensioned in the axial direction when the joint housing is closed. The axial pretension is applied to compensate for any changes when the bearing shell settles and/or the bearing surfaces wear down.
However, it has been observed that anchoring the plastic bearing shell in the joint housing in this way often fails to satisfy the requirements of the ball-and-socket joints with respect to load-bearing capacity, fail-safe operation and torsional stiffness of the bearing shell, as well as manufacturing costs. One reason is that the bearing shell of conventional ball-and-socket joints is typically secured in the joint housing by an axial force or shape engagement, or through an axial pretension, which is frequently inadequate to permanently fix the position of the bearing shell in the joint housing due to the load applied to the ball-and-socket joint during operation.
Moreover, manufacturing tolerances in the bearing shell and the joint housing, as well as poor reproducibility of the attachment, can lead to significant variations in the quality of conventionally manufactured ball-and-socket joints. This is particularly the case with the commonly used connection between the bearing shell and the joint housing which is based on forming or flanging the bearing shell or producing an edge on the joint housing. The connection between a conical bearing shell and a conical joint housing in conventional ball-and-socket joints produced by pressing the bearing shell into the joint housing is also poorly reproducible. It is also not possible with conventional ball-and-socket joints to afterward adjust, for example, the play or other tolerances in order to reduce unacceptable manufacturing tolerances, because the conventional ball-and-socket joints can typically not be adjusted after assembly.
Consequently, a bearing shell that is essentially affixed in the joint housing in the axial direction through shoulders or limit stops, is frequently unable to permanently satisfy today's requirements with respect to torsional stiffness of the bearing shell in the joint housing, reproducible manufacturing tolerances of the ball-socket joint dimensions, and absorbing large radial loads and shocks. This situation can be aggravated if other types of stress are generated when the ball-and-socket joint is exposed, for example, to vibrations, aggressive substances and/or abrasive materials, which occurs frequently in automobiles.
It would therefore be desirable to provide a ball-and-socket joint that eliminates the aforedescribed disadvantages and that significantly improves anchoring of the bearing shell in the joint housing, while also improving the cost structure and process reliability in manufacturing.